Two layers of Cuprinol later (left over from my wife’s fence painting project earlier in the year), the new mobile wooden HEQ5/EQ6 will be ready for vanishing with yacht varnish once it dries – and with high humidity levels at present and low temperatures I think it might take a few days before it properly dries out from the water based Cuprinol. That’s the price you pay for using left over stuff!
The next step for my new mobile base for my HEQ5/EQ6 mount was to fill any holes in plywood spaces between strips wood left when we put it together and sand it down – photo below from part way through thus process.
Now that I am doing astrophotography, it is important that I create stable, mobile base to allow me to roll the mount in and out of the log cabin. The more that can remain set-up between sessions, the easier it will be to image – especially important in the UK as weather liable to deteriorate again quickly.
Angella & Alan came around today and helped me build a fantastic base – thanks Angella & Alan!
Paul has come up with this ingenious solution to the problem of a cricked neck when looking through the polarscope on these popular Sky Watcher mounts.
The photos below show how the 90 degree viewer and fitting are assembled, noting the nut used to clamp it together.
Paul has very kindly made one of these for me using a second hand Nikon DR3 right angle camera attachment off ebay (approx. £6). He has made the hole in the plastic fitting a tight fit on the short thread of the DR3 such that no nut is needed. He has learnt how to carefully enlage the bore of the plastic fitting so it is a snug fit in the polarscope eyepiece…a bit tedious because it’s trial and error and must be done very carefully to ensure that the bore is not accidently made too large. Patience needed and lots of cups ot tea! The finished product is a tight fit and needs screwing onto the thread of the viewer. It should be a snug push fit onto the polarscope eyepiece. Paul used a 32mm Waste Compression End Plug costing £1.50 from “Discount DIY Store”, Swadlincote High Street, Swadlincote, Derbyshire, UK.
In use: Fit collar to viewer first, then push it onto polarscope eyepiece as far as possible – see photo. Try different angular positions if its too tight to go on. The collar should go over the eyepiece and over the polarscope tube as well.
To focus polarscope, Paul has found that he needs to unscrew eyepiece about 5mm so he fitted an 0-ring onto the thread for eyepiece to clamp against and keep eyepiece tight in the focused position.
Got home from the trustees meeting last night to a glorious clear sky. On a Monday? Really?
I made an aperture mask for my dob over the weekend and was itching to try it out. The idea behind the mask is that on bright targets cutting out a bit of light and diffraction from the secondary struts should improve clarity, even though the aperture is reduced (350 to 160 in this instance).
And so after failing to resist temptation I was setup by 11:20:
Jupiter: Disappeared behind neighbors house. Need to catch it in the gap between house and apple tree 1.
Saturn: Seeing dreadful without mask: boiling away with no clarity at all. With the mask: same but dimmer. Hmmm.
Pluto: Spent ages looking for this. Definitely in the right place. Pluto formed a triangle asterism with two other faint stars. I upped the magnification to dim the sky glow and there was definitely something there. Wobbled the scope – that helped. Averted vision- didn’t make much difference. So- I’ve looked at Pluto but not seen it! Beginning to regret doing this on a work night…
Jupiter again. Behind apple tree 1. That moved quick! Damn!
Izar: At last- some success. Successively improved views moving from Baader zoom to binoviewers to adding aperture mask. In the final view the stars were pinpoint sharp and well separated with the companion showing a lovely blue.
Double double: the same experience. The 2 pairs were easily separated in all 3 configurations, but the binoviewers plus aperture mask gave the best view.
M13: Too dim for the mask, the best view was in the binoviewers- resolving all the way to the core and seemingly spherical, even though at that distance you don’t really have depth perception!
Jupiter again: Gotcha! Just before it snuck behind apple tree 2… Definitely a better view with the aperture mask- slightly dimmer but with much more clarity. 6 bands plus the GRS were clearly visible, with some detailing on the bands, plus the moons spread out as clear disks 3 to one side and one on the other.
Well worth the fatigue today!
Very pleased with the aperture mask- it’s not often an astro upgrade is almost free. It’s only really good for bright objects and with the binoviewers I had to velcro 4kgs onto the bottom of the tube to balance it- bit well worth the hassle!
After hearing about the rapid set up and simplicity of a Dobsonian mount for casual observing, I thought I would investigate how to get one as an alternative to my EQ5. Strange that these mounts cannot be bought separately, except at Orion Optics UK, where I was quoted a high price. This set me on the DIY route.
I decided that I wanted the capability to adjust the tube axially (for balancing) and rotationally (for comfotable viewing position), as with the EQ5.I also wanted easy transfer of the tube between Dob and EQ5 (no tools needed). After a week of research, I settled for a hybrid that included a features from this article: http://www.scopemaking.net/dobson/dobson.htm, The Sky at Night articles in Dec 2014 and Jan 2015 and the Orion Optics design. Originally, I was going to design the rings and dovetail bar to be interchangeable, but when a set became available I settled on a separate ring set for each mount.
I won’t go into detail about the build/assembly but show various stages in pictures. The main stages are; 1.mods to the ring set, 2.cutting, shaping and painting, 3.bearings and the 4.optional brake. Anyone who wants more detail please contact me.
1. Modify ring/rails assembly.
Trunions: PVC 160mm pipe plugs (Buildbase, Newhall, Swadlincote). Protect bearing surface with masking tape. Locate centre and fix to bar with 1/4″UNC fasteners (Pugh & Sanders Ltd Burton on Trent).
Shape and fit 2nd ‘rail’ from 10mm plywood. Fix to rings with 1/4″ csk head screws. Locate trunion on centreline in same position exactly as other trunion.
Trial fit completed ring/rail assembly to scope
2.Cutting, shaping and painting frame
I used 18mm mdf for the base and sides and 10mm plywood for the front, back, rail and accessory tray. Use plastic fixing blocks and screws to hold everything together. No adhesive needed. Take basic dimensions from the article referenced above, except width of front and back, noting that alt bearing box is not needed and friction brake needs to be included.
Mark out parts using trammel to draw circular base.
Cut with jigsaw and smooth with rasp and glasspaper
To obtain width of front and back, measure distance between trunion flanges and add 10mm.
Use plastic fixing blocks to assemble, drill through upper base and screw to frame, bolt to lower base, trial-fit scope assembly. If all goes pear shaped, use as a ‘lazy-susan’ coffee table!
Trial fit 3 feet 120° apart.
Use jigsaw and ripsaw to cut holes to reduce weight and improve appearance.
Hang from washing line for painting – 2 coats minimum. Have a coffee between coats!
For altitude bearing use two 2mm thick ptfe sheets, drilled and countersunk in centre for small csk head screw.
For azimuth bearing use 3 Magic Glides (Wickes) spaced 120° apart within 300mm circle .
Use M10x60mm carriage or ordinary bolt and M10 Tee Nut (Amazon or ebay) inserted upside down for pivot in lower base. Tighten so it will not fall out or turn when M10 Nyloc nut is tightened.
For upper bearing use 12″ vinyl record (grooves make for low friction). To form a good bearing for the bolt in the upper base use a brass10-15mm reducer plumbing fitting (Wickes) drilled out to 10mm. Secure bases with oversize washer, spring washer and M10 Nyloc nut. Tighten only enough to take up slack.
Small spacers are needed to prevent sideways movement of scope assembly. Spacers are squares of ptfe fastened with small screw and spring washer fitted between side and flange of trunion. Trial fit to to gauge the spacer size and position of spacers.
4, Friction Brake Feature – Optional
This feature prevents the scope moving if the assembly becomes out of balance, although there is the option to slide the tube axially.
Attach another strip of ptfe to top of curved section of brake. Attach small hinges between brake and side using small 90° brackets to allow screwing into face of wood – mdf will split if screwed into edge! Attach a ‘Brighton sash window catch’ (satin chrome finish from Screwfix) such that it can be released to allow the scope to be lowered into place and tightened to stop movement or lock the scope. Fit accessory tray to front and hooks to sides for clipboard, glasses etc. Extension legs can be used if elevation is low or if the ground is long wet grass. To make carrying more comfortable, fit a length of 12mm soft clear plastic hose cut lengthways to upper curve of the front.
I had great fun making this but have used it only briefly to observe the Moon and was pleased the way it moved…but I still like the fine control provided by my EQ5 control cables. Now how can I add this feature to the Dob…?
Next stage of my video eyepiece construction completed today, ready for testing hopefully tomorrow evening which is predicted to be clear.
In the first photo, the components are connected and working. In the second photo, I have assembled everything into single unit. The photo below shows the video eyepiece with lens on it rather than 1.25 inch telescope adapter.
Roger suggested this project at a RAG meeting and kindly sent me a list of required components. The project is to produce an electronic eyepiece based on PD camera with small screen next to it so that observers can get the benefit integrated video images with their improved limiting magnitude over the eye at a glass eyepiece whilst retaining the “At the telescope” experience and not requiring user to carry lots of kit into the field. The mantra is simple, easy and effective, with the visual observer in mind at all times. The components required include the PD camera, which I already had, 7 inch LED screen, a 12V to 5V converter, various connectors and small 12V battery to power it all.
Main task is to add in converter and connect all so that single 12V power connection with power both PD camera and the 5V screen as well.
I successfully achieved this today. Next step will be shrinking it all down into a neat package and working out how I am going to attach the screen to the PD camera.